1. Field of the Invention
The present invention relates to a vehicle surroundings monitoring apparatus that extracts objects by performing binarization processing of images taken by infrared cameras.
Priority is claimed on Japanese Patent Application No. 2004-347334, filed Nov. 30, 2004, the content of which is incorporated herein by reference.
2. Description of Related Art
Conventionally, a display processing device is known in which an object such as a pedestrian with a possibility of colliding with a vehicle is extracted from an infrared image of a vehicles surroundings captured by an infrared camera, and information of this object is provided to the driver (for example, see Japanese Unexamined Patent Application, First Publication No. H11-328364).
This display processing device searches a region (binarized object) where bright parts are concentrated by binarizing the infrared image, and determines whether or not the binarized object is a pedestrian's head based on the distance calculated from an aspect ratio or filling factor of the binarized object, and also an actual area and a center of gravity on the infrared image. Then, the height of the pedestrian on the infrared image is calculated from the distance between the head part region of the pedestrian and the infrared camera, and an average height of adult persons, and a body region containing the body of a pedestrian is set. By separating and displaying the head region and body region from other regions, visual aid for the driver is performed with respect to a pedestrian.
Moreover, a technique is known which searches a region (binarized object) where bright parts are concentrated by binarizing the infrared image, extracts the image region at the same distance from that of the binarized object in the vertical direction of the binarized object, and calculates the height of the object at the same distance from that of the binarized object from the binarized object and the image region to recognize that the object is a pedestrian (for example, see Japanese Unexamined Patent Application, First Publication No. 2003-216937).
Incidentally, since the display processing device of the example of the related art mentioned above detects a pedestrian based on determination of the shape for a head part region or body part region on the infrared image, it may become difficult to distinguish a pedestrian from a manmade structure that has a shape of a pedestrian, and particularly a similar shape, size, and position height of the pedestrian's head and that emits heat.
Moreover, in Japanese Unexamined Patent Application, First Publication No. 2003-216937, the pedestrian recognition is simply performed by calculating the height of the object based on the binarized object and the image region at the same distance as that of the binarized object in the vertical direction of the binarized object, on the infrared image, and the single search region is simply set at each predetermined height in the vertical direction of binarized object. Therefore a problem arises in that the height of the binarized object in the gray scale image cannot be accurately calculated in the state where for example the object is inclined with respect to the vertical direction.